I stand partly corrected. I only knew for certain servlet spec 2 was out in 99, and had not known anyone doing Java web serving stuff. I had colleagues doing java, and I worked in a commercial web house with those same colleagues, but none seemed to consider java web stuff (server side) usable (again memory's a bit hazy). I do know by 2000 some jumped in to servlets big time, but not many before that.
I think my first was perl/cgi in Jan 96 - not a full "web app" but I could read and write data via web forms to a database (msql IIRC). Feb 96 I know I was doing some PHP/FI, though still did a lot of Perl for years, mostly because that's what most hosts supported. For my own stuff, it was generally PHP even then when I had a choice.